Some handheld tools produce haptic output through their normal operation. For example, a power drill has a motor which produces vibrations and transmits those vibrations to the user through its handle. These vibrations caused by the drilling action can provide some haptic information. For example, a user that is familiar with the drill can discern when the drill's motor is going slower than usual for some amount of pressure applied to the trigger and material to be drilled. The user could guess that the bit is too hot or dull, that the material is harder than other materials, or that the drill's battery needs recharging. Rather than being left to guess, the user may want more meaningful haptic feedback while using a noisy tool. Although some haptic cues can be discerned, noisy tools do not provide many meaningful haptic cues, especially in comparison to their manual counterparts.
Typically, when a handheld tool such as a power tool operates, it produces a haptically noisy environment. That is, it provides such strong haptics naturally, that it can overpower other haptic feedback. For example, a user drilling through wood may not feel the vibration of a cell phone in their pocket while drilling, even though the location of the phone's vibration is not near the drill.
It may be convenient to a user to receive haptic feedback information from a tool that is in addition to haptic feedback naturally being provided by the tool. Conventional systems, however, can only provide haptic information when there is not another haptic output of the handheld tool to contend with.